Developers of electronic devices have struggled with designing user interfaces for data entry of ideographic characters. Ideographic characters are commonly used for Asian languages, such as Chinese and Japanese. These Asian languages include a large quantity of ideographic characters, in excess of 13,000 characters. In contrast, a standard full-size alphabetic keyboard, such as a standard QWERTY keyboard, only has about 100 keys or so. It is quite challenging to design an electronic device that will permit a user to input the 13,000 or more characters of an Asian language using the limited quantity of keys of a standard full-size alphabetic keyboard.
The problems of designing a user interface for data entry of ideographic character in a portable electronic device are even more challenging. The increasing demand for small, handheld devices is driving keyboard design towards keypad data entry. A keypad typically has only 12 to 24 keys of which 10 keys are used for entering numbers 1 through 9 and 0. The keypad is typically used on telephones, mobile telephones and similar portable electronic devices. One hand of a user supports the device and the other hand accesses the user interface to enter data. It is more difficult to design a user interface for a portable electronic device, since there are far fewer input keys available for entry of ideographic characters.
Schemes of character entry using a 9-key or 10-key keypad have been proposed. Several of these schemes are based on entry of strokes and other character components. For example, Chinese Patent Applications No. CN1142631A and CN1120695A describe three categories of character components are mapped to keys on a keypad:—lines, corners and boxes. Whereas such a scheme is flexible, it does not have any inherent ergonomic efficiency, as there is no intuitive relationship between keys and character components. Also, in decoding key entry, it is a drawback that the user must enter not just 1 to 3 initiated strokes, but also 2 or 1 of the last strokes of a character. This requirement causes the user to have to think ahead to the last stroke of a character to enable complete character entry. It is believed that this requirement is improved or disambiguation because the selection of strokes and boxes inadequately spans the range of stroke components required for data entry and therefore inadvertently disambiguates strokes.
Also, U.S. patent application Ser. No. 09/220,308, filed on Dec. 23, 1998, assigned to the assignee of the present invention, describes a keypad for stroke-based ideographic text entry where each key has a clear and reasonably unambiguous stroke meaning. For this keypad, the selected strokes assigned to keys are capable of addressing the 13,000 or more characters of an Asian language. Also, the layout of the keypad provides a particular association between a key and its corresponding stroke. In particular, corner-shaped strokes are positioned at the corners of the keypad so that a user may locate them easily. In addition, the corner-shaped strokes are positioned in locations that predominantly correspond to the positions where they appear in the majority of characters that include these components. Further, the keys of the left-hand column represent strokes that predominate in left-hand portions of characters and radicals, and the keys of the right-hand column represent strokes that predominate in right-hand portions of characters and radicals. Although the above design of the user interface is effective, there is an opportunity to improve upon this design.
There is a need for an improved keypad for stroke-based ideographic text entry in which each key has a clear and reasonably unambiguous stroke meaning while being capable of addressing the 13,000 or more characters of an Asian language. In particular, there is a need for a keypad that separates character strokes in the differentiating groups so that a user may intuitively and quickly locate the character strokes. In addition, there is a need for one or more short-cut buttons for the more common character stroke combinations appearing in the majority of characters of an Asian language while continuing to allow the user to manually input the character stroke combinations, if he or she so chooses not to use the short-cut.
It is further desirable to have a keypad for stroke-based ideographic text entry that conforms to existing standards of Asian countries. For example, the National Quality Technology Monitoring Bureau of the Peoples Republic of China has published an “Information Technology Generic Specification For Chinese Character Input With Digital Keyboard” which was approved on Mar. 17, 2000 and became effective on Jul. 1, 2000. Section 4.4.1 of this publication sets forth the basic stroke key position settings for numeric keys 1 through 5 as follows: key 1 is the heng stroke, key 2 is the shu stroke, key 3 is the pie stroke, key 4 is the dian stroke and key 5 is the zhe stroke. The publication does not provide stroke key position settings for the other keys of the digital keyboard.